On 05/09/2011 04:50 PM, Alan Stern wrote:
> On Mon, 9 May 2011, Jan Andersson wrote:
>
>> This patch changes the uhci_{read,write}* functions into using function
>> pointers from the uhci_hcd struct when accessing registers. This is done in
>> order to reduce the amount of code that need to be ifdef:ed around
>> uhci_{read,write}* when later adding (dynamic) support for big endian mmio.
>>
>> This change leads to a bit more work for the processor when running with
>> a PCI-only UHCI kernel. Considering how relatively slow PCI accesses are
>> it should not matter much, and it saves us the trouble of having a special
>> case for PCI-only configurations in uhci-hcd.h.
>>
>> Also added 'const' to uhci_hcd argument.
>>
>> Signed-off-by: Jan Andersson <jan@xxxxxxxxxxx>
>> ---
>>
>> My guess is that the change in this patch may not be to everyones (anyones?)
>> liking. Another solution would be to use someting more similar to the previous
>> version, like:
>>
...
>> ... or more similar to the solution in used for the EHCI HCD (leads to the
>> largest amount of special case ifdefs, at least in my attempts, but no extra
>> function call):
>>
>> #if !defined(CONFIG_USB_UHCI_SUPPORT_NON_PCI_HC)
>> static inline u32 uhci_readl(struct uhci_hcd *uhci, int reg)
>> {
>> return inl(uhci->io_addr + reg);
>> }
>> #else
>> #define uhci_has_pci_registers(u) ((u)->io_addr != 0)
>> static inline u32 uhci_readl(struct uhci_hcd *uhci, int reg)
>> {
>> if (uhci_has_pci_registers(uhci))
>> return inl(uhci->io_addr + reg);
>> #if defined(CONFIG_USB_UHCI_BIG_ENDIAN_MMIO)
>> elsif uhci_big_endian_mmio(uhci)
>> return readl_be(uhci->regs, reg);
>> #endif
>> else
>> return readl(uhci->regs, reg);
>> }
>> #endif
>
> I would really like to see no change to the object code in the PCI-only
> case.
>
> For the various non-PCI cases, imitating EHCI may be messy but it has
> the advantage of following a well-established precedent.
>
I was expecting that but had to try with the solution I thought was
easiest on the eyes :-). For V2 I will change to a solution like the
last one described.
Thanks,
Jan
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